0. Digital Microfluidics Control System II
P15610

1. Agenda Review Problem Statement Customer Requirements
Engineering Requirements
Risk Assessment
Market Comparison
Functional Decomposition
Morphological Chart
Concept Selection
System Architecture
Feasibility Analysis
Project Plan
Pat

2. Problem Statement
Current state - The current control system is not self contained and uses a class AB amplifier which makes the system large and nonmodular.
Desired state - A fully enclosed control system that efficiently operates the DMF chip while providing accurate feedback.
Project Goals - Make key improvements to functionality of control system, and complete all assigned deliverables.
Repeatable, consistent droplet motion.
Durable, lightweight, modular design.
Constraints - Use provided DMF chip, control fluid droplets using electrowetting, use DI water as test fluid, ensure compatibility with peripheral hardware and GUI.
Kenny

3. Customer Requirements
Zach H.

4. Engineering Requirements
Zach H.
Changed capacitance granularity

5. Risk
Assessment
Kevin

6. Market Comparison Parameters DropBot NeoPREP Capacitance Precision
~5pF
Not Specified
Droplet Speed Range
0-70mm/s
Impedance Precision
Cost
$1500
$150,000
Portability
Contained
Not Portable
Size
1’x1.5’x1’
5’x5’x5’
Mike

7. Market Comparison
DropBot
NeoPREP
Mike

8. Sandia Digital Microfluidics Hub
Pat
Start at 2:22

9. Functional Decomposition
Kevin

10. Morphological Chart
Pat

11. Concept Selection
Zach S

12. Oscillator and Demultiplexer
Temperature range:
-10C to 60C
Cost:
$1.00 each
Frequency:
100 kHz+
Size:
Diminutive
Zach S

13. Concept Selection
Zach S

14. Miniature Circuit Breaker
Trip conditions:
5A; 240V
Cost: $18.00
Size:
Deck of cards+
Zach S

15. Concept Selection
Kenny

16. Server Rack
Weight:
2.4 lbs
Cost: $60.00
Size: ~Toaster oven
Kenny

17. Concept Selection
Zach H

18. Mechanical Heat Sink With Fans
Airflow (HS/fan):
55/30 ft3 /min
Cost (HS/fan):
$45.00/$4.00
Weight (HS/fan): 1.4 lbs/<1 lbs
Size (both):
Deck of cards +
Zach H

19. System Architecture
Mike

20. Feasibility Analysis - Capacitive Measurements
Capacitive sensor circuit
Circuit should be able to measure 0.01pF change in capacitance
Sampling Frequency = 4MHz
Requires a comparator
Inexpensive (~$3.00)
Mike
Example Circuit

21. Feasibility Analysis - Amplifier
Amplifier Requirements
Input AC Voltage
~117 V
Input AC freq.
60 Hz
Peak Output Voltage
170 Vrms
Capacitive Load
10 nF
Cut off frequency
100 kHz
Voltage gain
~48 dB
Input Resistance
20 kΩ
Ambient Temp.
25 C
Requirements are based off the amplifier used in the previous project.
The current design will use two cascaded common emitter BJTs with a crystal oscillator providing a frequency of 100kHz.
Adam

22. Feasibility Analysis - Cost
Electrical Components
Cost (USD)
Control Board
$20.00
I/O Board
$50.00
Arduino Mega
$25.99
Crystal Oscillator
$1.00
Amplifier
$250.00
Mini Circuit Breaker
$5.00
Mechanical Components
Server Rack
$200.00
Fan + Heatsink
$60.00
Rough estimate of Total Cost ~ $600
Assigned budget is $2000
Adam

23. Feasibility Analysis - Weight
Kenny
Engineering Requirement: <13,600 g

24. Engineering Analysis to be Completed
Electrical
Component Tolerances
Noise Analysis
Power Consumption
Speed of computation
Mechanical
Structural
Shock & Vibration
Heat
Electrical Present First: Zach S
Mechanical Present Second: Pat

25. Project Plan
Pat

26. Questions?